Plant and Soil：中科院版纳植物园揭示持续干旱对西双版纳热带雨

伴随全球变暖，极端气候事件呈现频发趋势，特别是干旱事件发生的频率和强度都有明显增加。云南省在 2009至2010 年度发生了秋～冬～春连旱，被认为是云南有气象记录以来同期最严重的干旱事件，而随后的2011～ 2012年的持续干旱，更是引起了多方关注。

土壤呼吸是森林生态系统碳循环的重要组成部分之一，气候变化会对其产生潜在影响。若干旱导致土壤碳排放减少，则会在一定程度上减缓全球变暖;相反，若干旱导致土壤呼吸增加，则会形成正反馈，加剧全球变暖。因此，明确持续干旱对森林生态系统土壤碳排放产生何种影响，对于降低预测未来全球变化背景下碳循环响应的不确定性具有重要意义。

为探究长期干旱对西双版纳热带雨林土壤呼吸及碳循环的影响，中国科学院西双版纳热带植物园全球变化研究组博士研究生张翔在其导师、研究员张一平和沙丽清的指导下，基于设置在版纳植物园沟谷林内的热带雨林生态系统水分控制实验，对热带雨林在降雨持续减少情景下土壤呼吸速率的响应及其与土壤温湿关系的变化进行了研究。研究结果表明：持续干旱条件下，土壤呼吸速率在雨季期间有显著升高，而在干季期间与对照差异不显著。相关分析表明，降水减少会改变土壤呼吸与土壤湿度的关系，且存在季节差异。与热带雨林多年平均净生态系统碳交换量(NEE)相比，干旱引起的土壤呼吸年排放总量的增量十分可观，可以认为西双版纳地区发生干旱时土壤呼吸的变化可对森林生态系统碳收支产生重要影响。与其他热带地区降水控制试验结果比较后发现，样地的初始土壤含水量差异可能是造成土壤呼吸对干旱响应差异的重要原因。故在全球尺度上预测土壤呼吸对干旱的响应时，土壤湿度状况及季节的影响不容忽视。

相关研究结果以Effects of continuous drought stress on soil respiration in a tropical rainforest in southwest China 为题在线发表于土壤学期刊plant and Soil。

该研究得到了西双版纳热带雨林生态系统研究站和中心实验室的支持，获得了国家自然科学基金(U1202234，41271056，41071071)、中科院战略性先导科技专项(XDA05050601

原文链接：

Effects of continuous drought stress on soil respiration in a tropical rainforest in southwest China

原文摘要：

Background and aimsDrought is predicted to have a profound impact on soil respiration. This study aimed to assess the effects of long-term precipitation decrease on soil respiration in a tropical rainforest.MethodsA precipitation reduction experiment was conducted in a tropical forest in southwest China at the beginning of 2011. Soil respiration and environmental parameters were measured monthly for three years.ResultsThe continuous precipitation reduction treatment did not affect the seasonal patterns of soil respiration, but it significantly increased soil respiration in the study plot during the rainy season, and the relationship between soil respiration and soil moisture differed in the control and reduction treatment in the rainy season. Compared with the net ecosystem exchange of carbon in this system, the increment of annual soil carbon emissions in the reduction treatment was considerable and should not be ignored.ConclusionsOur results indicate that the responses of soil respiration to precipitation decrease may vary seasonally and the variation of volumetric water content in different seasons may be an important factor leading to the seasonal variation. The variation of soil moisture among different ecosystems as well as in different seasons should be taken into consideration when predicting the future response of soil respiration to drought globally.

DOI：10.1007/s11104-015-2523-4

作者：张一平和沙丽清